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AM5728: Pin drive strength

Michi Yama
Guru 10030 points

Part Number: AM5728

Hi,

I would like to know the PIN drive strength of gpio pin with 3.3V mode on AM5728.

According to the Table 5-17. Dual Voltage LVCMOS DC Electrical Characteristics on AM5728 DM, it is written that "Idrive is minimum 6mA". And then, the description is written as the below.

   " Pin Drive strength at PAD Voltage =0.45V or VDDS-0.45V"

This description is the same as 1.8V mode and 3.3V mode. Does this mean Pin Drive strength is 6mA regardless  the voltage mode? If it is yes, what is maximum of drive strength?

Please advise me.

I appreciate your quick reply.

Best regards,

Michi

  • 0
    TI__Guru**** 393215 points
    The factory team have been notified. They will respond here.
  • 0
    TI__Genius 13567 points

    Hi Michi,

    Can I ask why you would like to know the max pin current? Typically if you are planning to source or sink more 6mA it is better to use a buffer and not the output directly. The drive strength of a I/O pin is not constant. To start a state transition the current is high to meet timing requirements but when the output reaches a steady state the current is closer to 6mA and you should not try to use more.

    Regards,
    Ahmad

  • 0 in reply to Ahmad_Rashed
    Prodigy 10 points

    Dear Ahmad-san,

    Thank you for your reply.

    According to the data manual of AM5728, the drive strength is the below.

    Does this mean the driver current is guaranteed 6mA at least?

    Please advise me again.

    Best regards,

    Michi

  • 0 in reply to Ahmad_Rashed
    Guru 10030 points

    Dear Ahmad-san,

    Thank you for your reply.

    According to the data manual of AM5728,  the drive current is the below.

    Does this mean the drive current is guaranteed until 6mA at least?

    As to your advice, 6mA is typical value, I think. Customer need to know this pin's drive strength  for how many devices can be connected.

    Please advise me again.

    Best regards,

    Michi

  • 0 in reply to Michi Yama
    TI__Genius 13567 points
    Hi Michi,

    The answer to your question is not simple because the drive strength of the pin output is not constant nor limited. You should use the ibis model for timing analysis. The section called "Timing Requirements and Switching Characteristics" in the datasheet has information on the test circuit used to measure and meet the timing specifications listed. Compare that with the capacitive loading of the devices you plan to connect to the AM57x.
  • 0 in reply to Ahmad_Rashed
    Guru 10030 points
    Dear Ahmad-san,

    Thank you for your reply.

    I need more information regarding "Idrive" parameter.

    My customer would like to know "Idrive" . What is "Idrive" used to describe what parameters?

    In AM5728 DM, Table 5-17, "Idrive" is written in the below.

    "Pin Drive strength at PAD Voltage = 0.45V or VDDS-0.45V"

    In datil, where is "PAD voltage" ?

    Idrvie =6 mA (min.) with PAD voltage =0.45V or VDDS-0.45V, does this current value shows for each pin? Or does it shows total current value for all pins using same VDDS?

    I think this pin is not needed to have the buffer if it is used as 6mA source. Is my understanding right?

    Please advise me again.

    Best regards,
    Michi
  • 0 in reply to Michi Yama
    Guru 10030 points
    Hi,
    I issued new thread for my remaining question.
    Please continue to support me.

    Best regards,
    Michi